In related U.S. patent application Ser. No. 12/175,142, a compact zoom imaging system is described that utilizes a moveable mirror to select different fields of view for a series of images that are stitched together to form a wide angle image in a zoom system. Moveable mirror devices for imaging systems require fast actuators that can move mirrors of relatively large size, have 2 axes of movement, have low power requirements, can produce large deflections and low cost in a compact form factor. In addition, for a moveable mirror device for the zoom system as disclosed, the mirror only needs to operate to a series of known positions. However, the positioning of the mirror at these known positions must be done reliably with high accuracy.
Moveable mirror systems can be formed with a variety of actuators to tip and tilt the mirror. Thermal actuators, magnetic actuators, electrostatic actuators and piezoelectric actuators have been used to make different types of moveable mirrors for beam steering applications.
U.S. patent application Ser. No. 2008/0165402 discloses a moveable plate that can be used with a mirror in an optical scanner. However, the moveable plate as disclosed has relatively short piezoelectric actuators that are constrained in the way they work against each other so that the performance is limited to smaller deflections. In addition, the piezoelectric actuators are designed to operate over a continuous range of positions so that the repeatability and accuracy of positioning the moveable plate is limited and complex control circuitry with positional feedback is required to improve the repeatability and accuracy. Further, the actuators are located outside the mirror so that the movable plate assembly is substantially bigger then the movable plate.
World International Patent Organization Patent Application 2006/110908 describes a displaceable platform that can be tipped and tilted by 4 piezoelectric actuators. However, the piezoelectric actuators are curved so that the MEMs device is difficult and expensive to make. In addition, the curved nature of the piezoelectric actuators increases the overall size of the device.
Therefore, a need exists for a low cost moveable mirror that is small in size and can rapidly and repeatably move to a series of known positions with accuracy.